When they did not consume fluids some were already moderately dehydrated after the 100 minutes. Their average body mass reduction was 3.9% (± 0.7%), which is only just within the mild dehydration guidelines of a loss of 1-4% of body mass.

Three per cent dehydration is the equivalent of having a Blood Alcohol Content (BAC) of 0.08 which has been found to slow down the response time of drivers by 17 per cent and increase the chances of having a car accident by five times.

When the surfers did consume fluids during their 100 minute session they only experienced a 1.6% (± 0.7%) body mass reduction.

Performance Losses Analysed:

For those who did not consume fluids, their dehydration resulted in a 20.3% (± 7.1%) decrease in surfing performance in the last 20 minutes of their session, compared with the first 20 minutes. Those who consumed fluids were actually surfing better during the last 20 minutes than they were at the start.

Not consuming fluids also led to a significant impairment of information processing speed, visual motor skills, visual acuity, short-term memory, working memory and attention.

Upper and lower-body muscular endurance were also diminished by 21.2% (± 5.5%) and 4.4% (± 5.8%), respectively, compared with a 17% (± 4.1%) reduction in upper body muscular endurance for those who consumed fluids. Their lower body muscular endurance remained largely unchanged.

Analysing these results, the study said that given surfing relies heavily on ”decision-making, reaction times, short-term memory, proprioception and information processing ability”, the decline in cognitive function could be a more significant influence on surfing performance than the decline in neuromuscular ability.

Surfing Increases Fluid and Sodium Losses:

While being soaked in sweat may resonate with the concept of bodily fluid loss, the human body does sweat in the ocean – we just don’t notice it – while wetsuits can increase these sweat rates, requiring increased fluid intake (the 12 surfers analysed in the study were all wearing wetsuits).

In fact just being in water causes chemical reactions in the body that increases fluid and sodium losses, according to research cited in the study.

Furthermore being immersed in water has been found to supress the human body’s thirst sensation, which is why you may not feel thirsty when surfing for long periods.

Surfing Dehydration Awareness and Prevention:

Research into competitive surfers cited in the study found “competitors made little to no attempt to hydrate prior to, during, or after training”. Furthermore, being unable to hydrate during a surf session further exacerbates dehydration risks.

Given the significant losses of cognitive ability, muscular endurance and surfing performance experienced by surfers who did not hydrate during their session, there is a strong case for pre-surf hydration.

Furthermore, with performance losses so significant after only a 100 minute surf session, and with many surfers staying in the water for four to five hours or more, there is also a strong case to exit the water and consume fluids mid-surf.

Consuming an electrolyte drink with sodium, magnesium and other amino acids – the loss of which increases when exercising in the water – will also help you surf your best.